Pilot structure for vaporizing burners



J y 1950 D. A. CUSTANCE 2,513,551

PILOT STRUCTURE FOR VAPORIZING BURNERS Filed April 17, 1947 J I 1 m O 0 K O O Patented July 4, 19 50 PILOT STRUCTURE FORQVAPORIZING BURNERS Douglas A. Custanc'e, Royal Oak, Mich, assignor to Columbus Metal Products, Inc., Columbus, Ohio, a corporation of Ohio Application April 17, 1947, Serial No. 741,995

I My invention relates to a liquid fuel burner and has for one purpose to provide improved pilot means for such a burner.

Another purpose is to provide a pilot structure for a pot type liquid fuel burner in which the pilot structure is in the center of the pot, or removed from the side wall of the pot.

Another purpose is to provide improved means for supplying air to the pilot mixture in 'a' pot type burner.

Another purpose is to provide improved means for admitting liquid fuel to a pot type burner, said fuel admission means having associated therewith an improved pilot structure.

Other purposes will appear from time to time in the course of the specification and claims.

I illustrate my invention more or less diagrammatically in the accompanying drawings, wherein:

Figure 1 is a vertical axial section; and

Figure 2 is a section on the line 2-2 of Figure 1.

Like parts are indicated by like symbols throughout the specification and drawings.

Referring to the drawings I generally indicates an outside housing or drum which may, for convem'ence, be made cylindrical but which may be of any other suitable form. In the particular structure herein shown I illustrate a cylindrical drum having ground engaging supports 2 separated by air admitting spaces 3. The drum is partly closed adjacent its lower end by a'partition 4 having a central air admitting aperture 5. A supporting ring 6, which is shown as angular in radial cross-section, receives and supports-the top flange 8, of a burner pot I. The burner pot includes a circumferential side wall shownas generally cylindrical or slightly downwardly tapered. It is closed at the bottom by a bottom wall or end wall 9. The burner pot side wall is shown as having a plurality of primary air inlet apertures l spaced circumferentially about the pot and located at various distances from the endsof the pot. Any suitable means may be employed for admitting secondary air to the mixtured primary air and vaporized liquid fuel. I illustrate for example a single row ll of secondary air inlets, shown as upwardly and inwardly inclined, and as both larger and more closely spaced than the primary air inlets Ill. The otherwise open top of the pot is partly closed by a flame ring l2 which may be centrally apertured as at l3.

l4 generally indicates a conventional liquid fuel control means adapted to control the rate of flow of liquid fuel to the burner. It may, for example,

5' Claims. (Cl. -158 91) be a conventional float valve assembly. It may receive liquid fuel from any suitable source not herein shown, and may deliver such liquid fuel along the supply duct IS. The rate of flow of liquid fuel along the duct l5 may. be controlled in any suitable manner, either automatically or 1 upon the bottom wall of the pot and is vaporized by the heat of combustion taking place in or above the pot. The vaporized fuel rises in the pot and is mixed with the primary air delivered through the inlets ID. A primary or rich mixture of va- I porized fuel is thereby formed. As this mixture rises in the pot and flows toward the flame aperture l3, it receives an additional supply of secondary air through the inlets I I. This secondary air, supplied to the rich mixture, completes a thinner and fully "combustible mixture which burns atjor-above the plane of the secondary air inlets ll-QThe flame rises through the flame outlet'or" aperture l3- of the flame ring 12 and extends up into the heater space surrounded by the upper housi'ngor-drum portion 20.

It will be understood that the burner may be turned down to a minimum rate of flow, at which time it burns with a minimum or pilot flame. A

purpose of the-present invention is to insure a' minimum turndown in connection with a clean pilot fiame'which results in little or no release or'dep'osit of free carbon or other undesired byproducts of combustion.

Referring to the drawings I illustrate a generally cylindricalpilot piece25 having a circumferential sidewall 26 and a top wall 27. The side wall 26 is provided with a plurality of air apertures 2B which are spaced circumferentially around the pilot piece and are shown as arranged in a plurality of rows at different levels. Air is admitted to the interior of the pilot piece, for example through the air inlet tube 29 which is open at the top and bottom and which admits outside air to the interior of the pilot piece. The lower edge of the pilot piece may be notched or apertured as at 30 to permit the escape of liquid fuel not vaporized in the pilot piece.

Surrounding the exterior of the pilot piece I illustrate a circumferential Wall 3| which may be foraminous and which surrounds a space which is open at the top, as at 32. Primary air is admitted through the tube 29, and forms, with the vaporized liquid fuel, a primary mixture. This primary mixture flows outwardly into the space between the Walls 28 and 3i and receives secondary air through the inlets of the wall 31. At minimum fuel flow there may be combustion within the pilot piece 25 itself. Or I may find it advisable to proportion the parts and to control the rate of fluid flow in such fashion that a secondary or fully combustible mixture is formed in the space surrounded by the wall 31 and is there burned.

When the rate of liquid fuel flow is either manually or automatically increased, then the liquid fuel cannot all be vaporized in the pilot piece or in the space within the Wall 3 I. The unvaporized liquid then flows out over the exterior portions of the bottom wall .9, and the result is the vaporization of an increasing volume of liquid fuel. This increased volume of vaporization raises the combustion level in the pot, until, at high fire, all of the apertures ll] are supplying primary air to the richmixture, and it is not until this rich mixture receives secondary air through the apertures II that final combustion can take place. On the other hand, when the user, either manually or by automatic control, reduces the flow again to the pilot rate, the much smaller volume of liquid delivered can be vaporized in the pilot piece, or on the bottom wall just outside of the pilot piece, and localized pilot combustion takes place.

It will be realized that whereas I have described and shown a practical and operative device, nevertheless many changes in the size, shape, number and disposition of parts may be made withoutdeparting from the spirit of my invention. I therefore wish my description and drawings to be taken as in a broad sense illustrative or diagrammatic, rather than as limiting me tov my precise showing.

I claim:

1. In a pilot structure for pot type burners, adapted for use in a pot having a bottom wall and a circumferential side Wall with air inlet apertures therein, and having a liquid fuel inlet and an air inlet, both located in the bottom of the pot, a pilot piece having a top wall and a circumferential side wall defining and surrounding a primary chamber in communication with said fuel inlet and air inlet of the pot, said side wall having a plurality of air outlets located at various levels and adapted to permit the escape of air from said primary chamber, a circumferential outside wall surrounding the pilot side wall and defining, with it and the bottom of the pot, an open topped circumferential mixing and combustion space radially restricted to provide a chimney action, said circumferential side wall of the primary chamber being apertured to ad- 4 mit liquid fuel from the primary chamber, for vaporization, to said chimney space.

2. The structure of claim 1 characterized by said circumferential outside wall being foraminous.

3. The structure of claim 1 characterized by some of said pilot sidewall outlets being located above the top of the circumferential outside wall, the circumferential outside wall being shorter than the side Wall of the pilot piece.

1 4. In combination, a burner pot having a bottom wall and a circumferential side wall having :a plurality of air inlet apertures spaced circumferentially thereabout and located at various levels-therein, a liquid fuel duct extending to said pot and communicating with the interior of the pot through an aperture in the bottom of the pot spaced inwardly from the pot side wall, an air inlet duct extending upwardly from the bottom of the pot and formed and adapted to admit outsideair upwardly through the bottom of the pot, a primary pilot housing including a circumfer ential side wall and a top wall, said housing defining a space surrounding and in direct communication with the delivery .points of liquid fuel and of airthrough said liquid fuel and air inlets, said circumferential side wall having a plurality of air outlets spaced circumferentially thereabout and located at various levels therein, said side wall being additionally apertured to permit liquid fuel to flow outwardly therethrough, and an outside wall surrounding and spaced outwardly from said circumferential wall and defining therewith, and with the bottom of the pot, an open topped chimney space.

5. The structure of claim 4 characterized by said outside wall being foraminous and adapted to admit air from the interior of the pot to the open topped chimney space about the circumferential side wall of the pilot housing.

DOUGLAS A. CUS'IANCE.

REFERENCES CITED The following references are of record in the Great Britain Jan. 25 1938 

